Recovery of particulate carbon from synthesis gas

ABSTRACT

A process for recovering particulate carbon from the effluent gas stream from a partial oxidation synthesis-gas generator by scrubbing the effluent gas with water in a scrubbing zone to form a carbon-water dispersion, by mixing said dispersion with a liquid organic extractant comprising a mixture of the liquid organic by-products from the oxo or oxyl process so as to produce a clarified water layer and a carbon-extractant dispersion, by separating and recycling said clarified water to said scrubbing zone, and by introducing part or all of said carbon-extractant dispersion to said gas generator as at least a portion of the generator feedstock.

This is a division of application Ser. No. 535,606 filed Dec. 23, 1974,now U.S. Pat. No. 3,980,591.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a continuous process for recoveringparticulate carbon from synthesis gas, and particularly fromcarbon-water dispersions.

2. Description of the Prior Art

Raw synthesis gas leaving a partial oxidation synthesis gas generatorcomprises principally CO and H₂ together with minor amounts of finelydivided carbon or particulate carbon. Preferably, the particulate carbonis removed from the effluent gaseous stream by contacting the gas withwater in quenching and scrubbing zone. The water wets and agglomeratesthe finely divided carbon soot particles so as to form a mixture ofparticulate carbon and water. The particulate carbon produced insynthesis gas manufacture is unique, and problems associated with theseparation of synthesis gas carbon are not the same as those encounteredin the removal of carbon or solids made by other processes. For example,the fine carbon particles from partial oxidation are unusual in thattypically particulate carbon produced by the synthesis-gas-generationprocess will settle in water to a concentration of only about 1.0 to 3.0weight percent, whereas conventional carbon blacks may settle toconcentrations of as much as 10 weight percent.

To produce synthesis gas economically, it is important to separateclarified water from the carbon-water mixture for reuse. However, thefine particle size of the carbon soot makes ordinary filtration methodsdifficult and makes gravity separation uneconomical because of excessivesettling times i.e. about 1-2 days. Further, liquid hydrocarbonextraction procedures for recovering particulate-carbon soot arecomplex. In a prior process by R. M. Dille et al., U.S. Pat. No.3,147,093, a hydrocarbon oil was added to the water-carbon mixture tofacilitate separation, but this procedure resulted in the formation ofsoft aggregates of carbon curds contaminated with oil. Further, undersome conditions troublesome emulsions which are difficult to separatemay form in the resulting oil-carbon-water dispersion. By the process ofour invention, particulate carbon mixed with the organic extractant isquickly and easily separated from quench and scrubbing water, so as topermit recycle of the clarified water.

The oxo process is the commercial application of a chemical reactioncalled oxonation or, more properly, hydroformylation. In this reaction,hydrogen and carbon monoxide are added across an olefinic bond toproduce aldehydes containing one more carbon atom than the olefin.

The oxyl process is a method for directly producing alcohols bycatalytically reducing carbon monoxide with hydrogen so as to linkseveral partially reduced carbon atoms together. Essentially it is amodified Fischer-Tropsch Process which preferentially producesoxygenated compounds consisting mainly of alcohols.

SUMMARY

The subject process relates to the recovery of particulate carbon fromthe effluent stream of synthesis gas i.e. mixtures of H₂ +CO, producedby the partial oxidation of a hydrocarbonaceous feedstock in asynthesis-gas generator at a temperature in the range of about 1300° to3500° F and a pressure in the range of 1-300 atmospheres. The effluentgas stream from the gas generator is scrubbed with water in a scrubbingzone to produce a carbon-water dispersion. Then in a mixing zone aliquid organic extractant comprising a mixture of the liquid organicby-products from the oxo or oxyl process preferably containing a minimumof water-soluble components is mixed with the carbon-water dispersion inan amount sufficient to render all of the carbon particles in saiddispersion hydrophobic and to resolve said carbon-water dispersion. Nextin a separating zone, such as a decanter, a stream of clarified waterand a dispersion of particulate carbon in said extractant, whichdispersion floats on said clarified water layer, are separately removed.In another embodiment, the liquid organic extractant is added in twostages.

The clarified water may be recycled to said scrubbing zone, preferablyafter at least a portion of any dissolved water-soluble constituentsfrom said extractant are removed. The carbon-extractant dispersion maybe introduced into the synthesis-gas generator as at least a portion ofthe feedstock. However, it may first be mixed with freshhydrocarbonaceous feed and preheated or vaporized. Preferably, thesynthesis gas is produced at the proper pressure and H₂ /CO mole ratiofor direct feeding into said oxo or oxyl process in which said mixtureof liquid organic by-products is produced for use as said extractant.

Optionally, by an additional step the carbon-extractant dispersion maybe concentrated in a centrifuge prior to being introduced into the gasgenerator as at least a portion of the feed. The comparatively clearthin stream from the centrifuge is then mixed with the carbon-waterdispersion as at least a portion of said liquid organic extractant.

DESCRIPTION OF THE INVENTION

Synthesis gas comprises principally H₂ and CO and may contain relativelysmall amounts of CO₂, H₂ O, CH₄, H₂ S, N₂, COS, A, particlate carbon andfuel ash. It may be made by partial oxidation of a hydrocarbonaceousfuel feedstock in a free-flow synthesis gas generator. For example aliquid hydrocarbon fuel, such as fuel oil, is reacted with afree-oxygen-containing gas and stream at an autogenously maintainedtemperature within the range of about 1300° to 3500° F and at a pressurein the range of 1 to 300 atmospheres.

By scrubbing the effluent gas stream from the gas generator with waterin a gas-scrubbing zone, particulate carbon may be removal from the gasstream as a pumpable or free-flowing carbon-water dispersion containingabout 0.2 to 3 weight percent carbon. This carbon-water dispersion isthen mixed with a liquid organic extractant in a mixing zone. Theextractant comprises a mixture of liquid organic by-products from an oxoor oxyl process to be more fully described.

The amount of extractant is sufficient to render all of the carbonparticles in the carbon-water dispersion hydrophobic and to resolve thecarbon-water dispersion. As further described below, the extractant maybe added in one or two stages. The total extractant forms with thecarbon from the carbon-water dispersion a pumpable carbon-extractantdispersion containing about 0.5 to 5 wt. % carbon. A clarified waterlayer separates out in a decanter and sinks to the bottom. The waterlayer is removed from the decanter and may be recycled to the scrubbingzone, preferably after purification by flashing to remove traces ofhydrocarbons. The carbon-extractant dispersion which forms and floats onthe water layer in the decanter may be removed and treated or utilizedfurther or introduced into the gas generator as at least a portion ofthe fuel.

Gaseous inpurities in the effluent gas stream from the synthesis gasgenerator may be removed in a manner to be more fully described toproduce synthesis gas e.g. mixtures of H₂ + CO having a mole ratio H₂/CO in the range of about 0.9 to 2.0 moles of H₂ per mole of CO.Synthesis gas may be produced having a specific H₂ /CO mole ratio forintroduction into an oxo or oxyl process.

In one embodiment of the invention, the mixtures of carbon monoxide andhydrogen produced in the synthesis gas generator with a H₂ /CO moleratio in the range of about 1-2 moles of the H₂ per mole of CO are usedin the well known oxo process in which carbon monoxide and hydrogen areadded to an olefin in the presence of a cobalt catalyst at e.g. atemperature in the range of about 100° to 200° C and a pressure in therange of about 65 to 300 atmospheres to produce an aldehyde containingone carbon atom more than the original olefin. Thus, a hydrogen atom andformyl group may be added across the double bond of an olefin as shownin equations (1) and (2)):

    RCH = CH.sub.2 + CO + H.sub.2 → RCH.sub.2 CH.sub.2 CHO (1)

    RCH = CH.sub.2 + CO + H.sub.2 → RCH(CHO)CH.sub.3    (2)

optionally, normal alcohols may be produced from the normal aldehydes byhydrogenation as shown in equation (3)

    RCH.sub.2 CH.sub.2 CHO + H.sub.2 → RCH.sub.2 CH.sub.2 CH.sub.2 OH (3)

the oxo reaction is homogeneously catalyzed by carbonyls of group VIIImetals, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium,irridium, and platinum. However, cabalt is the only metal whose carbonylcatalysts are of industrial importance e.g. CO₂ (CO)₈, HCo(CO)₄, and Co₄(CO)₁₂.

Reaction times vary in the range of about 5 to 60 minutes. The synthesisgas feed to the oxo or oxyl process contains 1-2 moles of hydrogen permole of carbon monoxide.

Various olefinic raw materials include ethylene to producepropionaldehyde, propylene to produce butyraldehyde, and pentylenes,heptylenes, nonylenes, and dodecylenes used to produce higher oxoalcohols. Dimers and trimers of isobutylenes may be used. Straight chainproducts are favored over branched-chain products. For example, normalbut not isobutyraldehyde can be converted into butanol or2-ethyl-1-hexaol. Lower temperatures and higher carbon monoxide pressurefavor the straight-chain isomers.

Processing steps required to produce an oxo product economically include(1) hydroformylation, or oxo reaction in an oxo reactor at a temperaturein the range of about 100°-200° C and a pressure in the range of about65-500 atm and preferably in the range of about 200 to 300 atm; (2)removal of catalyst from the reaction mixture (decobalting); (3) cobaltcatalyst recovery and processing for reuse; (4) aldehyde productrefining; and optionally, (5) hydrogenation at a temperature in therange of about 50°-250° C, and at a pressure in the range of about50-3500 psi to produce alcohols; and (6) alcohol refining. Oxo productsand by-products e.g. aldehydes, alcohols, are usually refined byconventional distillation equipment. Chemical treatment may be used toremove trace quantities of impurities.

The oxyl process as defined herein is a method for producing a mixtureof oxygenated organic compounds by catalytically reducing carbonmonoxide with hydrogen at a temperature in the range of about 175° to450° C and a pressure in the range of about 10 to 200 atmospheres. TheH₂ /CO ratio may be in the range of about 0.9 to 2 moles of H₂ per moleof CO. Space velocities may range from 100-500 SCF of dry feed per cu.ft. of cat. per hr., and higher, based on fresh food. Both fused andprecipitated iron catalysts may be used. The iron catalyst may containcopper, calcium oxide, diatomite, and may be impregnated with potassiumhydroxide. Iron nitride catalysts may be used.

The oxyl process for producing alcohols may be illustrated by Equation(IV);

    2n H.sub.2 + nCO →C.sub.n H.sub.2n♭1 OH + (n-1) H.sub.2 O (IV)

the alcohols may be subsequently converted to olefins and paraffins.

Essentially the oxyl process is a modified Fischer-Tropsch process whichpreferentially produces oxygenated compounds consisting mainly ofalcohols. In addition to predominantly straight-chain alcohols and a fewside-chain alcohols, by-product esters, other oxygen-containingcompounds, paraffin hydrocarbons, and olefins may be produced. Theolefins may be treated by the oxo process (hydroformylation followed byhydrogenation) to increase the yield of alcohols.

For example, a mixture of oxygenated compounds containing approximately30% alcohols in addition to acids, aldehydes, olefins, and esters may beproduced by converting gaseous mixtures of H₂ + CO over alkalized ironfillings at 150 atmospheres pressure and at a temperature of 400°-450°C.

Another oxyl process operates at a pressure in the range of about 10 to50 atmospheres and at a temperature of about 175°-230° C. Fused-ironcatalysts, of the conventional ammonia-synthesis type, and high spacevelocities are used. Gas recycle to increase the catalyst life may beemployed: 7-20 volumes of recycle gas per volume of fresh synthesis gas.Straight chain alcohols, e.g. up to C₁₂, may be produced by thisprocess.

By-products as defined herein are normally liquid organic co-productsformed in the hydroformylation or oxyl process and consist of liquidorganic materials from the group consisting of alcohols, aldehydes,esters, ketones, ethers, acids, olefins, saturated hydrocarbons, andmixtures thereof.

A particular advantage of the subject invention is that the stream ofsynthesis gas may be produced in a synthesis gas generator at a properpressure for direct use in the oxo or oxyl process, with gaspurification but without gas compression. A costly gas compressor maythereby be eliminated. Also, the liquid by-products from the oxo or oxylprocess, which may have previously presented a disposal problem may nowbe economically used as an extractant for resolving carbon-waterdispersions produced in the synthesis gas scrubbing zone and as agenerator feedstock.

The term liquid organic extractant as used herein by definition shallmean a mixture of liquid organic by-products from the oxo or oxylprocess comprising at least one alcohol and at least one ester inadmixture with at least one other constituent and preferably two or moreether constituents from the group listed in Table I. Also shown in TableI is the range of carbon numbers for the organic constituents. Theseorganic compounds may have straight chains or branched structures. Thespecific composition of the liquid extractant will depend upon thereaction conditions, the type of reactants, and the procedure used torefine the product. The term liquid organic extractant includes wholesamples and fractions thereof, and the raffinate after water extractionof said whole samples or fractions thereof. Preferably, the liquidorganic extractant contains a minimum of water soluble compounds.

The amount of each constituent in the liquid organic extractant may betaken from the ranges shown in Table I. If a group of compounds ispresent, there may be more than one compound in that group present inthe liquid organic extractant. For example, if the liquid organicextractant contains 65 wt. % of normal and isoalcohols and 18 wt. % ofesters, then the total remaining constituents in the extractant cannotexceed 17 wt. %. The term by-products includes by definition the liquidorganic waste products from the oxo or oxyl process, which have thecomposition shown in Tables I and II.

                  TABLE I                                                         ______________________________________                                        Ingredients in Liquid Organic "Extractant"                                    From Liquid Organic By-Products of Oxo or Oxyl                                Process                                                                       ______________________________________                                        Group          Carbon Range Wt. %                                             ______________________________________                                        Alcohols       C.sub.3                                                                              to    C.sub.16                                                                            2    to  75                                 Esters         C.sub.6                                                                              to    C.sub.28                                                                            5    to  70                                 Aldehydes      C.sub.3                                                                              to    C.sub.16                                                                            Nil  to  25                                 Ketones        C.sub.3                                                                              to    C.sub.16                                                                            Nil  to  25                                 Ethers         C.sub.6                                                                              to    C.sub.28                                                                            Nil  to  50                                 Acids          C.sub.3                                                                              to    C.sub.16                                                                            Nil  to  10                                 Olefin         C.sub.5                                                                              to    C.sub.15                                                                            Nil  to  30                                 Saturated Hydrocarbons                                                                       C.sub.5                                                                              to    C.sub.28                                                                            Nil  to  50                                 Water                             Nil  to  15                                 ______________________________________                                    

The range of ultimate analyses of liquid organic extractants derivedfrom liquid organic by-products of the oxo or oxyl process is shown inTable II. The elements will lie within the approximate ranges shown, solong as the total wt. % is 100.

                  TABLE II                                                        ______________________________________                                        Ultimate Analysis of Liquid Organic Extractant                                Derived From Liquid Organic By-Products of Oxo                                or Oxyl Process                                                               ______________________________________                                                      Wt. %                                                           ______________________________________                                        Carbon          About 55 to 90                                                Hydrogen        About  5 to 17                                                Oxygen          About  3 to 40                                                ______________________________________                                    

The preferred maximum concentration of organic acid present in theextractant is less than 5 wt. %, for example 1-2 wt. %. The organicesters are the reaction products of primary saturated alcohols andlow-molecular-weight saturated organic acids.

The composition of a typical mixture of liquid organic by-products of anoxo process for the production of butyraldehyde as produced for exampleby the process shown in Hydrocarbon Processing, page 211, November 1969,Gulf Publishing Co., Houston, Texas is shown in Table III.

                  TABLE III                                                       ______________________________________                                        Composition of Typical Mixture of Liquid Organic                              By-Products From An Oxo Process                                               ______________________________________                                                          Wt. %                                                       ______________________________________                                        Esters              54                                                        Ethers              20                                                        Aldehydes           5                                                         Ketones             5                                                         Acids               About 5 and below                                         Olefins             About 1 and below                                         Saturated hydrocarbons                                                                            About 1 and below                                         n-butyl alcohol     3.4                                                       i-butyl alcohol     0.6                                                       Alcohol (C.sub.5 -C.sub.8)                                                                        3.0                                                       Water               2                                                         ______________________________________                                    

The esters in the aforesaid typical mixture have an average carbonnumber of 12 and may be formed by the reaction of C₄ to C₉ alcohols andC₃ to C₈ acids. The ethers are highly branched and have an average C₁₂number. The ketones have an average C₁₂ number, and the acids have a C₃-C₅ number. The ultimate analysis of said typical mixture in wt. % isshown in Table IV.

                  TABLE IV                                                        ______________________________________                                        Ultimate Analysis of Typical Mixture of Liquid                                Organic By-Products From An Oxo Process                                       ______________________________________                                                      Wt. %                                                           ______________________________________                                        Carbon          69.2                                                          Hydrogen        12.0                                                          Oxygen          18.8                                                          ______________________________________                                    

Other properties of said typical mixture are shown in Table V.

                  TABLE V                                                         ______________________________________                                        Properties Of Typical Mixture of Liquid                                       Organic By-Products From An Oxo Process                                       ______________________________________                                        Gravity ° API 29.2                                                     Density, 0.87                                                                 Viscosity, Centistokes 68° F. 4.1; 122° F 2.0                   Distillation, ASTM                                                            Vol. %   ° F.                                                                             Vol. %    ° F.                                      ______________________________________                                        IBP      290       60        422                                              10       326       70        450                                              20       344       80        484                                              30       360       90        526                                              40       376       95        532                                              50       396       EP        564                                              ______________________________________                                    

It has been found that improved results can be obtained by using as theliquid organic extractant only a light fraction of the typical mixturedescribed in Table III. Said typical mixture was derived from theaforesaid oxo process and was then fractionated in a Hempel Flask andFractionating Column per ASTM Test Method D285-62. A cut comprising upto 60 volume %, for example the cut comprising up to 25% by volume, andpreferably the cut comprising up to 10% by volume will give good andsharp separations of the extractant soot mixture from water. Thepreferred 10% by volume fraction has an initial atmospheric boilingpoint (i.b.p.) of about 192° F and the 10 volume % boiling point ofabout 300° F. ASTM-D285-62. The composition of this i.b.p. - 300° F.mixture is shown in Table VI.

                  TABLE VI                                                        ______________________________________                                        Composition of I.B.P. - 300° F. Mixture of                             Liquid Organic By-Products From An Oxo Process                                ______________________________________                                                           Wt. %                                                      ______________________________________                                        n-Butanol            47.9                                                     Isobutanol           10.9                                                     Ispropanol           0.2                                                      Isopentanol          1.0                                                      Isohexanol           1.0                                                      Ketones, C.sub.3 -C.sub.5                                                                          2.0                                                      Esters, C.sub.6 -C.sub.8                                                                           18.0                                                     Acids, C.sub.3 -C.sub.5                                                                            5.0                                                      Water                14.0                                                     ______________________________________                                    

Said i.b.p. - 300° F mixture in Table VI has a gravity °API of about 35and an ultimate analysis as shown in Table VII.

                  TABLE VII                                                       ______________________________________                                        Ultimate Analysis of i.b.p. - 300° F. Mixture of                       Liquid Organic By-Products From Oxo Process                                   ______________________________________                                                      Wt. %                                                           ______________________________________                                        Carbon          62.2                                                          Hydrogen        11.1                                                          Oxygen          26.7                                                          ______________________________________                                    

There are preferably none of the following materials in the extractant:salts, sulfuric esters (sulfates), alkane or alkyl sulfonic acids,amine, amino, and ammonium compounds.

Preferably, by conventional methods e.g. flashing, extraction,distillation, and decanting, the water and water-soluble constituentsare removed from said liquid organic extractants prior to mixing theextractant with the carbon-water dispersion.

The synthesis gas generator in my process preferably consists of acompact, unpacked, free-flow noncatalytic, refractory-lined, steel,pressure vessel of the type d described in coassigned U.S. Pat. No.2,809,104 issued to D. M. Strasser et al., which patent is incorporatedherewith by reference.

The free-oxygen-containing gas may be selected from the group consistingof air, oxygen-enriched air (22 mole percent O₂ and higher), andpreferably substantially pure oxygen (95 mole percent O₂ and higher).

Preheating of the reactants is optional but generally desirable. Forexample, a hydrocarbon oil and steam may be preheated to a temperaturein the range of about 100° to 800° F. and the oxygen may be preheated toa temperature in the range of about 100° to 1000° F.

A wide variety of hydrocarbonaceous fuels is suitable as feedstock forthe partial oxidation process, either alone, in combination with eachother or with particulate carbon, and preferably in combination withsaid carbon-liquid organic extractant dispersion. For example, from 1 to90 parts by weight of carbon-extractant dispersion may be mixed witheach part by weight of the hydrocarbonaceous feed or mixtures thereof.The hydrocarbonaceous feeds include fossil fuels such as variouspetroleum distillates and residues, naphtha, gas oil, residual fuel,reduced crude, fuel oil, whole crude, coal-tar oil, shale oil, andtarsand oil. Slurries of solid carbonaceous fuels, i.e., lignite,bituminous and anthracite coals, and particulate carbon in water orliquid hydrocarbons are also suitable and are included herewith aswithin the scope of the definition for hydrocarbonaceous fuel feeds.

It is normal to produce from hydrocarbonaceous fuel feeds by partialoxidation about 0.5 to 20 weight percent of free-carbon soot (on thebasis of carbon in the hydrocarbonaceous fuel feed). The free-carbonsoot is produced in the reaction zone of the gas generator for example,by cracking hydrocarbonaceous fuel feeds. Carbon soot will preventdamage to the refractory lining in the generator by constituents whichare present as ash components in residual oils. With heavy crude or fueloils, it is preferable to leave about 1 to 3 weight percent of thecarbon in the feed as free-carbon soot in the product gas. With lighterdistillate oils, progressively lower carbon-soot yields are maintained.

The amount of soot in the product synthesis gas may be controlledprimarily by regulating the oxygen-to carbon ratio (O/C, atom/atom) inthe range of 0.7 to 1.5 atoms of oxygen per atom of carbon in the feedand, to some extent, by regulating the weight ratio of H₂ O tohydrocarbonaceous fuel feed in the range of 0.15 to 3.0 pounds of H₂ Oper pound of hydrocarbonaceous fuel feed.

In the above relationship, the O/C ratio is to be based upon (1) thetype of free-oxygen atoms in the oxidant stream plus combined oxygenatoms in the hydrocarbonaceous fuel feed molecules and (2) the total ofcarbon atoms in in the hydrocarbonaceous fuel feed plus carbon atoms inrecycled soot. Since the oxo and oxyl by-products contain combinedoxygen atoms, the requirement of free oxygen for gasification is lessthan for ordinary hydrocarbon. In fact, there is a synergistic effectleading to even lower oxygen consumption than would be expectedaccording to direct proportionality.

H₂ O is principally introduced into the reaction zone to help controlthe reaction temperature, to act as a dispersant of thehydrocarbonaceous fuel fed to the reaction zone, and to serve as areactant to increase the relative amount of hydrogen produced. Othertemperature moderators include CO₂ -rich gas, a cooled portion ofproduct gas cooled off-gas from an integrated ore-reduction zone,nitrogen, and mixtures thereof.

Many advantages are achieved in the subject process by the addition ofoxygen containing hydrocarbon materials, such as found in the liquidorganic extractant, as a portion of the feed to the synthesis gasgenerator. For example, for a given level of soot production, the amountof free oxygen supplied to the reaction zone of the snythesis gasgenerator, and the stream to fuel weight ratio may be decreased at asubstantial cost savings.

The free-carbon soot leaving the reaction zone entrained in the streamof product synthesis gas has some unique properties. It is bothhydrophilic and oleophilic. It is easily dispersed in water and has ahigh surface area. For example, the specific surface area of thefree-carbon soot, as determined by nitrogen absorption, ranges from 100to 1,200 square meters per gram. The Oil Absorption Number, which is ameasurement of the amount of linseed oil required to wet a given weightof carbon soot, ranges from 1.5 to 5 cc's of oil per gram of carbonsoot. For further information regarding the test method of determiningthe Oil Absorption Number see ASTM Method D-281.

Free-carbon soot, also referred to herein as particulate carbon, asproduced within our process has a particle size in the range of about0.01 to 0.5 microns and commonly has a diameter of about 77millimicrons. Free-carbon soot comprises about 92 to 94 weight percentof carbon, 1 to 4 weight percent of sulfur, and 3 to 5 weight percent ofash. Being formed at high temperatures, it is substantially free fromvolatile matter.

In one embodiment of our invention, the hot gaseous effluent from thereaction zone of the synthesis gas generator may be quickly cooled belowthe reaction temperature to a temperature in the range of 180° to 700°F. by direct quenching in water in a gas-liquid contacting or quenchingzone.

For example, the cooling water may be contained in a carbon-steel quenchvessel or chamber located immediately downstream from the reaction zoneof said gas generator. A large-diameter dip leg starting at the bottomend of the reaction zone and discharging beneath the water level in thequench chamber serves as an interconnecting passage between the reactionzone and the quench zone, through which the hot product gases pass. Thispassage also serves substantially to equalize the pressure in the twozones. A concentric draft tube, open on both ends, surrounds said dipleg, creating an annulus through which a mixture of quenched gas andwater rises vigorously and splashes against the support plate of thereactor floor. The water and gas then separate in the quench chamber inthe space outside the draft tube. This circulation of water through thedraft-tube system maintains the entire quench system at essentially thetemperature of the water leaving the quench vessel, which is also thetemperature of the saturated steam in the quench zone.

Recycle water from the carbon-scrubbing zone, to be further described,is normally introduced through a quench ring at the top of the dip-legto cool the metal at that point. Large quantities of steam are generatedin the quench vessel, and the quench chamber may be likened to ahigh-output high-pressure boiler.

The turbulent condition in the quench chamber, caused by the largevolume of gases bubbling up through said annular space, helps the waterto scrub a large part of the solids from the effluent gas so as to forma dispersion of uncovered particulate carbon and quench water. Further,steam requried for any subsequent shift conversion step is picked up bythe effluent synthesis gas during quenching. For a detailed descriptionof the quench chamber, reference is made to coassigned U.S. Pat. No.2,896,927 issued to R. E. Nagle et. al., which is herewith incorporatedby reference. Any residual solids in the cooled and scrubbed effluentsynthesis gas leaving the quench chamber may be removed by means of aconventional venturi or jet scrubber, such as described in Perry'sChemical Engineers' Handbook, Fourth Edition, McGraw-Hill Co., 1963,pages 18-55 to 56.

Alternately, the hot effluent gas stream from the reaction zone of thesynthesis-gas generator may be cooled to a temperature in the range ofabout 240° to 700° F. by indirect heat exchange in a waste-heat boiler.The entrained solid particles may be then scrubbed from the effluentsynthesis gas by contacting and further cooling the effluent stream ofsynthesis gas with quench water in a gas-liquid contact apparatus, forexample, a quench dip-leg assembly, a spray tower, venturi, or jetscrubber, bubble-plate contactor, packed column, or in a combination ofsaid equipment. For a detailed description of cooling synthesis gas bymeans of a waste-heat boiler and a scrubbing tower, reference is made tocoassigned U.S. Pat. No. 2,999,741 issued to R. M. Dille et al. andincorporated herewith by reference.

It is desirable to maintain the concentration of particulate carbon inthe gas-cooling and scrubbing-water streams in the range of about 0.5 -3 wt. % and preferably below about 1.5 wt. %. In this manner, thedispersion of carbon in water will be maintained sufficiently fluid foreasy pumping through pipelines and for further processing.

The temperature in the scrubbing zone is in the range of about 180° to700° F., and preferably in the range about 250° - 550° F. The pressurein the scrubbing zone is in the range of about 1-250 atmospheres, andpreferably at least 25 atmospheres. Suitably the pressure in thescrubbing zone is about the same as that in the gas generator, lessordinary pressure drop in the lines.

It is important with respect to the economics of the process that theparticulate carbon be removed from the carbon-water dispersion and theresulting clear water be recycled and reused for cooling and scrubbingadditional particulate carbon from the synthesis gas.

In the subject continuous process the previously described liquidorganic extractant comprising a mixture of liquid organic by-productsfrom the oxo or oxyl process is used to resolve the carbon-waterdispersion so as to separate the water from the carbon in single stageextraction. The total amount by weight of said liquid organic extractantthat is mixed with said carbon-water dispersion is in the range of about10 to 200 times, and preferably in the range of about 20-100 times theweight of the particulate carbon in the carbon-water dispersion. Thisamount is sufficient to render all of said particulate carbonhydrophobic and to resolve the carbon-water dispersion. Clarified waterseparates from the carbon-water dispersion and a carbon-extractantdispersion is produced.

The carbon-water dispersion may be contacted with said liquid extractantby any suitable means e.g. mixing valve, static mixer, baffled mixer,pump, orifice, nozzle, propeller mixer, or turbine mixer. High pressurewill make possible the use of an extractant containing lower-boilingconstituents. High temperature facilitates phase separation.

The mixed steam is passed into a phase-separation zone, for example adecanter or tank providing a relatively quiescent settling zone. In theseparating zone, also known as a decanter clarified water sinks to thebottom by gravity. A dispersion of carbon in said extractant may floaton top of the clarified water. The volume of the settling tank should besufficient to provide a suitable residence time preferably of at leasttwo minutes and usually in the range of about 5 to 15 minutes.

The pressure in the settling zone or decanter should be sufficient tomaintain both the extractant and the water in liquid phase, e.g. 5 to250 atmospheres, depending upon the temperature. The temperature, in thedecanter will be substantially that of the carbon-water dispersionleaving the scrubbing zone e.g. 180°-700° F., and preferably in therange of about 250°-550° F.

Clarified water is removed from the decanter, and at least a portion inadmixture with fresh water may be recycled to the scrubbing zone.Optionally, at least a portion of any dissolved water-solubleconstituents from the extractant may be removed from the clarified waterby conventional means before the water is recycled to the scrubbingzone. For example, the clarified water stream may be introduced into agas-liquid separation zone where the pressure is suddenly dropped. Alight gaseous fraction is flashed off which is cooled below the dewpoint to separate uncondensed light gases, water, and water solubleoxygen containing liquid organic compounds. A pumpable dispersion ofparticulate carbon in extractant containing about 0.5 to 5 wt. % solids,and preferably about 1.0 to 3 wt. % may be introduced into thesynthesis-gas generator as at least a portion of the hydrocarbonaceousfeed.

Optionally, said particulate carbon-extractant dispersion may bepreheated to a temperature in the range of about 200° to 800° F. orvaporized prior to being introduced into the gas generator. Optionally,about 0.01 to 99 parts by weight of said carbon-extractant dispersionmay be admixed with each part by weight of fresh hydrocarbonaceous fuelfeed, e.g. heavy fuel oil, before being introduced into the gasgenerator in a liquid or vapor phase. Alternatively thecarbon-extractant dispersion and oil mixtures may be burned as fuel in afurnace. In a separate embodiment to be further described, the aforesaiddecanter is combined with a centrifugal separator that furtherconcentrates the carbon-extractant dispersion.

Another embodiment of the invention involves two simultaneous additionsof liquid organic extractant in two continuous stages. Thus in the firststage, the aforesaid carbon-water dispersion is resolved into aclarified water layer and a dry carbon powder which floats on theclarified water. This may be accomplished by adding the liquid organicextractant to the carbon-water dispersion in an amount just sufficientto render all of the carbon hydrophobic but insufficient to produce acarbon-extractant dispersion at this stage. As a result of this smalleramount of extractant, the carbon separates rapidly and substantiallycompletely from the water and floats to the surface of theclarified-water layer as a dry-appearing, particularly agglomeratedspot.

The amount of liquid organic extractant to be added may be obtainedexperimentally by shake tests. Small increments of extractant are addedto the carbon-water dispersion until the carbon separates rapidly andfloats on the surface of the clarified water. Thus when the water phaseis clear and the carbon is "dry" and fluffy, the amount of extractant isoptimum. The amount of liquid organic extractant added in the firststage will usually fall within the range of about 1-3 times the OilAbsorption No. of the particulate carbon in the carbon-water dispersion.This amount may range between about 1.5 and 10 lbs. of extractant perlb. of carbon or preferably in the range of about 3 to below 6.

In the second stage the particulate carbon is floated off the surface ofthe clarified water layer in the decanter by introducing a horizontalstream of additional liquid organic extractant into said decanter at ornear the interface between said clarified-water layer and saidparticulate carbon.

A sweeping action across the interface will also disperse the carbon inthe extractant. The extractant in the first and second stages may havethe same or different constituents. However any extractant used conformsto those previously described -- see Tables I and II.

The principal advantage of the two-stage addition lies in the avoidanceof the formation of emulsions. In the first stage, the carbon-waterdispersion is resolved, and the carbon floats to the surface of thewater with the addition of a minimum of extractant. The secondary liquidorganic extractant is then added in much larger amounts with a minimumof mixing with the water so that emulsion formation is avoided even ifemulsifying agents are present.

The amount of liquid extractant that is introduced in the second stageis sufficient to form a carbon-extractant dispersion containing about0.5 to 5 wt. % carbon in the total extractant. This amount may be aboutten times the amount of extractant that was used in the first stage. Theclarified water is removed from the decanter in the manner describedpreviously.

In another embodiment of the process, a clarified or "thin" centrifugestream, to be further described, may be used as at least a portion ofthe liquid organic extractant in the single-stage operation of thedecanter. Alternatively, said clarified thin centrifuge stream may beused as the liquid organic extractant in extraction and decantation, asat least a portion of the liquid organic extractant in either saidsingle-stage extraction or in the first, second, or both stages of atwo-stage extraction.

In the centrifugal-separation zone, the carbon-extractant dispersion maybe separated into a "thick" centrifuge stream and a comparatively clean"thin" centrifuge stream of carbon-extractant. The thick centrifugestream may have a carbon content in the range of about 1 to 10 wt. % andsuitably about 4 to 7 weight percent. The thin centrifuge stream mayhave a carbon content in the range of about 0.02 to 1 wt. %, andsuitably about 0.1 to 0.5. The thick centrifuge steam ofcarbon-extractant may be then passed into the synthesis-gas generator asat least a portion of the hydrocarbonaceous feed. Optionally, from about0.01 to 99 parts by wt. thickened centrifuge stream may be mixed witheach part by wt. fresh hydrocarbonaceous fuel and fed to thesynthesis-gas generator. Optionally, these fuel streams may be used asfuel in a furnace. Further, these mixtures of hydrocarbonaceous fuel andcarbon-extractant streams may be preheated to a temperature in the rangeof about 100° to 800° F. They may be introduced into the gas generatorin liquid phase or vapor phase and may be in admixture with H₂ O.

The comparatively clean thin centrifuge stream of carbon-extractant ispassed into a hold-up tank where any waste gas is removed. At least aportion of the clarified thin centrifuge stream may be then recycled tothe extraction step. Clean water is removed from the bottom of thedecanter and recycled to the carbon-scrubbing zone. Preferably, at leasta portion of the water-soluble constituents of the extractant may beremoved from the water.

The pressure in the centrifuge may be in the range of about 1 to 200atmospheres. Centrifuges are normally constructed for operation atatmospheric pressure, but it would be advantageous to carry out thecentrifuging at a pressure only slightly below the decanter pressure,which is usually substantially lower than that of the synthesis-gasgenerator. The temperature in the centrifuge may be in the range ofabout ambient to 700° F.

Industrial centrifuges, such as described in Perry's Chemical Engineers'Handbook by Perry, Chilton, and Kirkpatrick, Fourth Edition,McGraw-Hill, Pages 19-86 to 19-100, employ centrifugal accelerationwhich is many times gravitational acceleration. The centrifugal forcecauses sedimentation of solid particles through a layer of liquid or thefiltration of a liquid through a bed of porous solids. Centrifugalforce, commonly expressed in multiples of the standard force of gravity,varies with the rotational speed and with the radial distance from thecenter of the rotating bowl. Continuous disc centrifuges are suitablefor use in the subject process.

Disc centrifuges, for example illustrated in FIG. 19-139 of Perry'sChemical Engineers' Handbook, develop 4,000 to 10,000 times the force ofgravity, and may go up to 20,000. Disc centrifuges have a bowl diameterin the range of about 7 to 32, a disc spacing in the range of about0.015 to 0.50 inches, number of discs in the range of about 30 to 130,and a disc half-angle in the range of about 35 to 50.

Although the process of the invention is particularly suitable forremoving substantially all of the dispersed particulate carbon from acarbon-water dispersion produced by water scrubbing the effluent gaseousstream from the partial oxidation process, it may be similarly used inmany other hydrocarbon gasification processes.

DESCRIPTION OF THE DRAWING AND EXAMPLES

A more complete understanding of the invention may be had by referenceto the accompanying schematic drawing which shows in FIG. 1 thepreviously described process in detail. Quantities have been assigned tothe various streams on an hourly basis so that the following descriptionin Example 1 may also serve as an example of the subject continuousprocess.

EXAMPLE I

With reference to FIG. 1 of the drawing, on an hourly basis about 14,400lbs. of a particulate carbon-water dispersion at a temperature of about250° F. and containing about 144 lbs. of carbon from the previouslydescribed gas-scrubbing zone of a process for making synthesis gas bythe partial oxidation of a hydrocarbonaceous fuel to be furtherdescribed are passed through line 1 into mixer valve 2, in which saidcarbon-water dispersion is mixed with 9216 lbs. of a liquid organicextractant from lines 3, 40, valve 41, and line 42. Valve 36 is closed.

The aforesaid synthesis gas is produced at a temperature of about 2400°F. and a pressure of about 30 atm. in a free-flow partial-oxidation gasgenerator (not shown). The composition of the synthesis gas in mole %follows: CO 41.00, H₂ 42.22, CO₂ 4.39, H₂ O 11.26, CH₄ 0.21, A 0.11, N0.12, and H₂ S+COS 0.69. About 144 lbs. of soot (particulate carbon plusash) are entrained in the generator-effluent gas.

About 9,966 pounds of hydrocarbonaceous charge stock are introduced intothe partial-oxidation synthesis-gas generator. This feedstream consistsof 82% heavy fuel oil plus 18% of a liquid extractant comprisingmixtures of by-products from an oxo process to be further described. Theultimate analysis of the mixture of by-products and heavy fuel oil inwt. % follows: carbon 81.22, hydrogen 11.37, nitrogen 0.48, sulfur 3.28,oxygen 3.45, ash 0.20. The gross heating value is about 17,814 BTU perpound and the gravity is 19.6° API.144lbs. of unreacted carbon plus ashare recovered by the subject process and are fed to the generator as aportion of the feed. 4,395 lbs. of steam and 10,183 lbs. of pure oxygen,contained in a stream of 99.5 mole percent purity, are also charged tothe generator.

After purification and drying to remove acid gases, H₂ O, andparticulate carbon, the synthesis gas is compressed and introduced intoan oxo process for the production of, for example, n-butyraldehyde bythe hydroformylation of proplyene in the presence of a cobalt catalystat a temperature in the range of about 130° - 175° C and a pressure ofabout 200 atm.

The liquid organic extractant in line 3 comprises a mixture of liquidorganic by-products from said oxo process having the composition shownin Table III and the Ultimate Analysis shown in Table IV in thespecification with substantially all of the water soluble compoundsremoved.

The mixture of said liquid organic extractant and carbon-water is passedthrough line 5 into decanter 6. A relatively quiescent volume isprovided in the settling zone at a pressure of about 25 atm.Substantially clear water, containing any dissolved water-solubleingredients from said extractant settles by gravity to the bottom ofdecanter 6 and flows out by way of line 7. Preferably, the water in line7 may be purified by suitable means and then recycled to the gas-coolingand scrubbing zone. A portion may be discharged from the system andreplaced by fresh water.

About 9,360 lbs. of a dispersion of particulate carbon and said liquidorganic extractant, containing about 144 lbs. of carbon are removed nearthe top of decanter 6 by way of line 8. About 2,822 lbs. of thiscarbon-extractant-water dispersion are passed through line 9 and line 10and into holding tank 11. Optionally, about 8,172 lbs. of fresh heavyliquid hydrocarbon fuel oil may be introduced into the system by way ofline 12, valve 13, and line 14 and mixed with the carbon-extractantdispersion in line 10. By means of pump 15, a carbon-extractant-oilmixture may be pumped from line 16 through lines 17, 18, and valve 19and line 20 into the reaction zone of said partial-oxidation gasgenerator (not shown) as said hydrocarbonaceous feed. Optionally, aportion of the carbon-extractant-oil mixture in line 16 may be passedthrough lines 17 and 25, valve 26, and line 27 into a furnace (notshown) as fuel. Similarly, about 7,422 lbs. of the extractant from line8 are passed through line 30, valve 31 and line 32 and car be utilizedin a furnace as fuel. It is usually desirable to operate the decanter ata pressure substantially below that of the gas generator.

In the aforesaid example all of the liquid organic by-products from anoxo or oxyl process were mixed with the carbon-water dispersion inmixing zone 2 in one stage. In another embodiment of the subjectprocess, addition of the liquid extractant may be done in two-stages.For example, with both valve 36 and valve 41 open, 432 lbs. of freshliquid organic extractant from lines 40, and 42 are introduced in thefirst stage into mixer 2 and mixed with the carbon-water dispersion fromline 1. Simultaneously, in the second stage, still with both valve 36and valve 41 open, about 8,784 lbs. of additional liquid organicextractant are passed through lines 35 and 37 into decanter 6 to sweepor float off the particulate carbon floating on the water surface. Therest of the process is substantially the same as previously described.Two-stage decanter operation will be described further in Example II.

EXAMPLE II

This example illustrates that embodiment where two separate andsimultaneous additions of liquid organic extractant of the typedescribed in Example I are made and are followed by centrifugalseparation of the carbon-extractant overhead from the decanter. Allquantities are on an hourly basis. This continuous process is shown inFIG. 2.

Example II is similar to the process in Example I, but provides for thetwo-stage addition of extractant. In the first stage, 432 lbs. of freshliquid organic extractant from line 3 are mixed in mixer 2 with 14,400lbs. of carbon-water dispersion, from line 1, containing about 144 lbs.of carbon; and the mixture is introduced into decanter 6 in the mannerdescribed previously in Example I. However the amount of liquid organicextractant added in the first stage is sufficient only to render all ofthe carbon in the dispersion hydrophobic. The carbon rises to the top ofthe decanter and floats on the clarified-water layer as a dry powder.The decanter is at a pressure of about 25 atm. Simultaneously in thesecond stage there is introduced into decanter 6 through line 5 about10,554 lbs. of additional liquid organic extractant, comprising aclarified thin centrifuge stream produced subsequently in the processand substantially comprising said liquid organic extractant plus anymake-up liquid organic extractant. This second stream of extractant isintroduced into the decanter near or at the interface between the carbonand the surface of the clarified-water layer. By this means theparticulate carbon may be floated off the surface of the clarified-waterlayer in the decanter. A carbon-extractant dispersion is therebyproduced, which is removed from decanter 6 by way of line 8 and passedinto centrifugal separation zone 10.

Substantially clear water, containing any dissolved water-solubleconstituents of said extractant, settles by gravity to the bottom ofdecanter 5 and is removed by way of line 7. Preferably, the water inline 7 may be purified by suitable means to remove the dissolvedwater-soluble constituents from the extractant and then recycled to thesynthesis-gas-cooling and scrubbing zone. A portion of this water may bedischarged from the system. About 11,130 lbs. of carbon-extractantdispersion from line 8, containing at least 144 lbs. of carbon togetherwith entrained water, are charged into a conventional continuouscentrifuge 10. The centrifuging speed is about 9500 revolutions perminute.

About 9,192 lbs. of a partially clarified thin stream of extractant areremoved from centrifuge 10 by way of line 11 and are introduced intoholding tank 12. Waste gas is discharged from the system through line 13and sent to flare. Optionally, this gas may be cooled below the dewpoint to separate out water and any condensible organic liquids. Acomparatively clean dispersion of particulate carbon and extractant isremoved through line 14, pumped by pump 16 into decanter 6 through line15, 17, 18, valve 19, and line 4. Optionally, additional liquid organicextractant as previously described may be introduced from an externalsource into the system through line 40, valve 41, and line 42. Forexample, liquid organic extractant from line 42 may be mixed in line 17with the thin centrifuge stream from line 15 prior to being introducedinto decanter 6 in the second stage. Alternatively, in the two-stageoperation of the decanter, by manipulating valves 46 and 19 separateportions of the thin centrifuge stream 15 may be passed into thefirst-stage mixer by way of lines 15, 17, 45 and 47; or into decanter 6in the second stage by way of lines 15, 17, 18, and 4; or into the mixerin the first stage and the decanter in the second stage.

About 2,224 lbs. of a thick centrifuge stream of particulate carbonmixed with extractant containing about 144 lbs. of particulate carbon,are removed from centrifuge 10 by way of line 20. Preferably, thisstream with or without preheat may be introduced into the synthesis-gasgenerator (not shown) as a portion of the feed by way of lines 21-23 andvalve 24. Optionally, heavy liquid-hydrocarbon fuel oil may beintroduced into the system by way of lines 25-26 and valve 27 and mixedin line 21 with said thick centrifuge stream. For example, 8,172 lbs. ofthe heavy fuel described in Example I are mixed in line 21 with thethick centrifuge stream from line 20. Optionally, the thick centrifugestream in line 20 may be passed through lines 21, 28-29, and valve 30 tobe burned in a furnace, for example, to produce steam. Optionally, heavyliquid-hydrocarbon fuel oil from line 25 also may be mixed with thisfurnace fuel. The thick centrifuge stream in line 23 may be introducedinto the gas generator in liquid or vapor phase. Preferably, it may bevaporized and dispersed in steam.

A variation in the aforesaid process may be the introduction of therequired amount of liquid organic extractant into decanter 6 in a singlestage. For example, with valve 19 closed and valve 46 open, the thincentrifuge stream from line 14 may be pumped into mixer 2 by way oflines 15, 17, 45, and 47. Any additional fresh liquid organic extractantrequired may be introduced through line 3 or 40 and passed into mixer 2.

Obviously, various modifications of the invention as herein before setforth may be made without departing from the spirit and scope thereof;and, therefore, only such limitations should be made as are indicated inthe appended claims.

I claim:
 1. A method for producing clean synthesis gas for the oxo oroxyl process comprising1. reacting by partial oxidation ahydrocarbonaceous fuel or a slurry of solid carbonaceous fuel withsubstantially pure oxygen in the reaction zone of a free-flownoncatalytic synthesis gas generator at a temperature in the range ofabout 1300° to 3500° F and a pressure in the range of about 1 to 300atmospheres in the presence of a temperature moderator to produce aneffluent gas stream comprising H₂ and CO and containing entrainedparticulate carbon and at least one member of the group CO₂, H₂ O, H₂ S,COS, CH₄, A, N₂, and mixtures thereof;
 2. introducing said effluent gasstream into gas cooling and gas scrubbing zones in which the gas streamis cooled and the entrained particulate carbon is removed, so as toproduce a carbon-water dispersion;
 3. removing gaseous impurities fromthe gas stream leaving (2), so as to produce a stream of synthesis gassubstantially comprising H₂ and CO;4. introducing the synthesis gas from(3) into an oxo or oxyl process for the production of liquid oxygencontaining hydrocarbons, and separating therefrom a mixture of liquidorganic by-products comprising at least one alcohol and at least oneester in admixture with at least one constituent from the groupconsisting of aldehydes, ketones, ethers, acids, olefins, saturatedhydrocarbons, and water;
 5. contacting said carbon-water dispersion from(2) with a liquid organic extractant comprising the aforesaid mixture ofliquid organic by-products from (4) in an amount sufficient to renderall of the carbon particles in said carbon-water dispersion hydrophobicand to resolve said carbon-water dispersion; and
 6. by decanting,separately removing in a separating zone a stream of clarified water anda pumpable dispersion having a carbon content of about 0.5 to 5 weight %and comprising said carbon particles and said liquid organic extractant;and wherein said separating zone is at a temperature in the range of180° to 700° F and a pressure sufficient to maintain both the extractantand water in liquid phase.
 2. The process of claim 1 where said liquidorganic extractant in step (5) is obtained by the fractionaldistillation of a mixture of liquid organic by-products from the oxo oroxyl process in step (4) and consists of the fraction up to 10 volume %and has approximately the following ultimate analysis in weight percent:carbon 62.2 hydrogen 11.1, and oxygen 26.7.
 3. The process of claim 1provided with the steps of mixing about 0.01 to 99.0 parts by weight ofsaid dispersion comprising said carbon particles and said liquid organicextractant from step (4) with each part by weight of freshhydrocarbonaceous fuel feed before being introduced into the gasgenerator.
 4. The process of claim 1 wherein said liquid organicextractant comprises the following mixture:

    ______________________________________                                        Group          Carbon Range Wt. %                                             ______________________________________                                        Alcohols       C.sub.3                                                                              to    C.sub.16                                                                            2    to   75                                Esters         C.sub.6                                                                              to    C.sub.28                                                                            5    to   70                                Aldehydes      C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   25                                Ketones        C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   25                                Ethers         C.sub.3                                                                              to    C.sub.28                                                                            Nil  to   50                                Acids          C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   10                                Olefins        C.sub.5                                                                              to    C.sub.15                                                                            Nil  to   30                                Saturated Hydrocarbons                                                                       C.sub.5                                                                              to    C.sub.28                                                                            Nil  to   50                                Water                             Nil  to  
 15.                               ______________________________________                                    


5. The process of claim 1 wherein said liquid organic extractantcomprises the following mixture:

    ______________________________________                                                          Wt. %                                                       ______________________________________                                        Esters              54                                                        Ethers              20                                                        Aldehydes           5                                                         Ketones             5                                                         Acids               About 5 and below                                         Olefins             About 1 and below                                         Saturated hydrocarbons                                                                            About 1 and below                                         n-butyl alcohol     3.4                                                       i-butyl alcohol     0.6                                                       Alcohol (C.sub.5 -C.sub.8)                                                                        3.0                                                       Water               2                                                         ______________________________________                                    


6. The process of claim 1 in which said hydrocarbonaceous fuel isselected from the group consisting of various petroleum distillates andresidues, naphtha, gas oil, residual fuel, whole crude, fuel oil,reduced crude; coal tar oil; shale oil; and tar sand oil; and saidslurry of solid carbonaceous fuel is selected from the group consistingof particulate carbon, lignite, bituminous and anthracite coal in wateror liquid hydrocarbon.
 7. A method for producing clean synthesis gas forthe oxo or oxyl process comprising:1. reacting by partial oxidation ahydrocarbonaceous fuel or a slurry of solid carbonaceous fuel withsubstantially pure oxygen gas in the reaction zone of a free-flownoncatalytic synthesis gas generator at a temperature in the range ofabout 1300° to 3500° F and at a pressure in the range of about 1 to 300atmospheres in the presence of a temperature moderator to produce aneffluent gas stream comprising H₂ and CO and containing entrainedparticulate carbon and at least one member of the group CO₂, H₂ O, H₂ S,COS, CH₄, A, and N₂ ;
 2. introducing said effluent gas stream into gascooling and gas scrubbing zones in which the gas stream is cooled andcontacted with water so as to effect the removal of said particulatecarbon from said effluent gas stream and to produce a carbon-waterdispersion;
 3. removing gaseous impurities from the gas stream leaving(2) so as to produce a stream of synthesis gas substantially comprisingH₂ and CO and having a mole ratio of about 0.5-2.0 moles of H₂ per moleof CO;
 4. introducing the synthesis gas from (3) into an oxo or oxylprocess for the catalytic production of aldehydes or alcohols andseparating therefrom a liquid organic extractant comprising a mixture ofliquid organic by-products comprising at least one alcohol and at leastone ester and at least one constituent from the group consisting ofaldehydes, ketones, ethers, acids, olefins saturated hydrocarbons, andwater;5. contacting said carbon-water dispersion from (2) in two stagesincluding in the first stage the step of mixing said carbon-waterdispersion with about 1.5 to 10 lbs. of said extractant from step (4)per lb. of carbon so as to render all of said particulate carbonhydrophobic and to release dry powdered carbon from said carbon-waterdispersion, with said carbon rising to the surface of said water in aseparating zone; and in the second stage introducing a stream of saidliquid organic extractant into said separating zone adjacent the watersurface so as to float off said carbon from a bottom layer of saidclarified water and to form a carbon-extractant dispersion containingabout 0.5 to 5 weight percent carbon.
 8. The process of claim 7 in whichthe amount of said liquid organic extractant mixed with the carbon-waterdispersion in the first stage on a weight basis is about 1 to 3 timesthe Oil Absorption Number of the particulate carbon as determined byASTM D281-31.
 9. The process of claim 7 in which said liquid organicextractant from step (4) is subjected to fractional distillation and thefraction up to 25 volume percent is used as the liquid organicextractant in step (5).
 10. The process of claim 9 in which said liquidorganic extractant is the fraction in the range of up to 10 volume % andhas a boiling point in the range of about i.b.p. to 300° F.
 11. Theprocess of claim 7 provided with the additional steps of withdrawingclarified water from the separating zone in step (5), removing at leasta portion of the dissolved water soluble constituents from saidclarified water, and recycling said purified water to the gas scrubbingzone in step (2) as said water.
 12. The process of claim 7 provided withthe additional step of introducing at least a portion of thecarbon-extractant dispersion from step (5) into the synthesis gasgenerator of step (1) as at least a portion of the feed.
 13. The processof claim 7 with the added steps of introducing said carbon-extractantdispersion from step (5) into a centrifuging zone at a temperature inthe range of about ambient to 700° F and a pressure in the range ofabout 1 to 200 atmospheres, separately withdrawing from saidcentrifuging zone a thick centrifuge stream of carbon-extractant and athine centrifuge steam of carbon-extractant; introducing said thickcentrifuge stream into said gas generator as at least a portion of saidhydrcarbonaceous fuel; degasifying said thin stream and introducing atleast a portion of said stream into said separation zone in either saidfirst, second or both stages as said stream of liquid organicextractant; withdrawing said clarified water stream from said separatingzone and removing from said water at least a portion of the dissolvedwater soluble constituents from said extractant; and recycling saidpurified water to said gas-scrubbing zone to scrub carbon from theeffluent gas stream leaving the gas generator.
 14. The process of claim13 provided with the steps of mixing about 0.01 to 99 parts by weight ofsaid thick centrifuge stream with each part by weight of freshhydrocarbonaceous fuel and introducing said mixture into said synthesisgas generator as feedstock.
 15. The process of claim 7 wherein theliquid organic extractant from step (4) contains substantially no watersoluble compounds.
 16. The process of claim 7 provided with theadditional step of introducing at least a portion of thecarbon-extractant dispersion from step (5), optionally in admixture withliquid hydrocarbon fuel into a furnace as fuel.
 17. The process of claim7 where in step (5) said liquid organic extractant is introduced in thesecond stage as a horizontal stream at or near the interface betweensaid clarified-water layer and said particulate carbon to sweep off saidcarbon and to form with it a carbon-extractant dispersion.
 18. Theprocess of claim 7 wherein the liquid organic extractant from step (4)comprises the following mixture:

    ______________________________________                                        Group          Carbon Range Wt. %                                             ______________________________________                                        Alcohols       C.sub.3                                                                              to    C.sub.16                                                                            2    to   75                                Esters         C.sub.6                                                                              to    C.sub.28                                                                            5    to   70                                Aldehydes      C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   25                                Ketones        C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   25                                Ethers         C.sub.6                                                                              to    C.sub.28                                                                            Nil  to   50                                Acids          C.sub.3                                                                              to    C.sub.16                                                                            Nil  to   10                                Olefins        C.sub.5                                                                              to    C.sub.15                                                                            Nil  to   30                                Saturated Hydrocarbons                                                                       C.sub.5                                                                              to    C.sub.28                                                                            Nil  to   50                                Water                             Nil  to  
 15.                               ______________________________________                                    


19. The process of claim 7 wherein said liquid organic extractantcomprises the following mixture:

    ______________________________________                                                          Wt. %                                                       ______________________________________                                        Esters              54                                                        Ethers              20                                                        Aldehydes           5                                                         Ketones             5                                                         Acids               About 5 and below                                         Olefins             About 1 and below                                         Saturated hydrocarbons                                                                            About 1 and below                                         n-butyl alcohol     3.4                                                       i-butyl alcohol     0.6                                                       Alcohol (C.sub.5 -C.sub.8)                                                                        3.0                                                       Water               2                                                         ______________________________________                                    


20. The process of claim 7 in which said hydrocarbonaceous fuel isselected from the group consisting of various petroleum distillates andresidues, naphtha, gas oil, residual fuel, whole crude, fuel oil,reduced crude; coal tar oil; shale oil; and tar sand oil; and saidslurry of solid carbonaceous fuel is selected from the group consistingof particulate carbon, lignite, bituminous and anthracite coal in wateror liquid hydrocarbon.